Transformer and method of operating same



n 3 L. c. NICHOLS 1,761,580

TRANSFORMER AND METHOD OF OPERATING SAME Filed April 10, 1922 Patented June 3, 1939 entree STATES LOUIS G. NICHOLS, OF WAUWA'IIOSA,

PATENT GFFICE ISCONSIN, ASSIGNOR TO ALLIS-CHALMERS MANU- WARE TRANSFORMER AND METHDD 0F OPERATING SAME Application filed April 10,

This invention relates to transformers, or other electrical apparatus, immersed in oil, and a method of operating same. It is particularly useful in connection with oil immersed transformers employing an overflow tank for the oil and in which the transformer casing is completely filled with oil. In transformers of this type, a pipe or conduit connects the transformer casing with the overflow tank, and in case it is desired to remove a closure such as a hand-pole plate in the cover of the casing, communication between said casing and the overflow tank is closed, the hand-hole plate removed, and the oil is then dipped out of the casing to reduce the level of the oil to a desired extent. This reduction in oil level is desirable in case it is desired to manipulate or work on parts of the transformer ordinarily immersed in the oil near the normal level thereof. Such a procedure is however highly inconvenient and not only usually results in oil being spilled over the transformer casing but by reason of carelessness in the use of dirty containers for dipping out the oil and pouring it back in, may result in the introduction of deleterious foreign substances into the oil. It is one of the objects of this invention to obviate these disadvantages.

Still another object is the provision of a means and method. of operation whereby a closure for a completely oil-filled transformer tank may be removed without necessity of dipping oil out of said tank or removing it in any other like manner. Other objects will appear hereinafter as the description of the invention proceeds.

The novel features of the invention will appear from this specification and the accompanying drawing forming a part thereof and disclosing one embodiment of the same, and all these novel features are intended to be pointed out in the claims.

The single figure of the drawing shows a transformer, partly in section, in which the invention has been applied, and one form of apparatus for carrying out the method of operation.

In the drawing, a transformer proper 1,

1922. Serial No. 551,260.

more or less diagrammatically indicated, is shown disposed in a casing which includes a tank 2. High and low tension leads 3, 4: respectively are indicated as being brought through insulators in a cover 5 which fits the tank 2 oil tight but need not necessarily fit it absolutely air or gas tight. The cover 5 is here shown as provided with a hand hole plate 6. An overflow tank 7, may be suitably mounted on a support 10. The overflow tank 7 is connected by means of a conduit 8 with a body of oil 16 contained in the tank 2. The opening of conduit 8 into the transformer casing is here shown as in the cover 5. The conduit 8 is preferably provided with a valve 9 by which communication between the casing, or tank 2, and the overflow tank 7 may be opened or closed. The overflow tank 7 may be provided with a glass level gauge 11.

The hand-hole plate 6 is here shown as provided with a nipple 12 to which may be connected a valve 13. An air pump 14 is here shown as permanently mounted on and connected to the valve 13, but this pump may be located elsewhere and it may also be arranged for mere temporary connection with the valve 13. As will appear hereinafter it is not necessary that the pump 14: be arranged to act through the hand-hole plate a 6; it may be connected to the transformer tank at any other suitable point. Moreover, any other suitable source of gas under pressure may be utilized. 1

The level 17 of the oil in the overflow tank 7 may be normally at any desired point. A pipe 18 communicates with the air above the surface or level 17, and the pipe 18 may have connected thereto a drier 19, open to atmosphere. The pipe 18 and drier 19 are however not necessary to the successful operation of the apparatus as far as the pres ent invention is concerned.

The transformer tank is here shown as provided with radiators 15 whereby the body ofoil 16 may be cooled.

The operation is as follows: As the o l 16 is heated up it expands and will pass up through conduit 8 into the overflow tank 7, air being driven out of the latter tank through pipe 18 and drier 19. When the oil 16 contracts the process is obviously reversed. If at any time it becomes desirable to remove a closure for the tank, as closure 6, air or gas is introduced into the transformer casing as for example by operating the pump 14 and opening the valve 13. The operator, having first noted the level 17 be fore commencing the introduction of gas, may note the amount that the level has been lowered in the main tank by noting the amount that the level rises in the gauge 11. The proportion between the rise of level 17 and the tall in level in the tank may readily be determined by experiment and this information may be furnished by the manufacturer. The foregoing is suggested as a convenient method of operation although of course other means and methods or" determining the level in the main tank will readily suggest themselves to those skilled in the art. Theamount that the level may be reduced in the main tank will depend on the position of the opening of the conduit 8 into said tank or cover thereof. It is obvious that this may be predetermined in any suitable manner so that the level in the main tank may be reduced to any desired value by displacing a given amount by a gas. Vhen the desired amount oi oil has been displaced the valve 9 may be closed. The hand-hole plate 6 may then be removed and it is clear that by the foregoing method of operation any overflowing of the oil from the main tank and all oil-removal operations as ordinarily necessary have been obviated. The oil is kept clean by temporarily storing it in the overflow tank 7. lVhen the desired work which necessitated the removal of hand-hole 6 has been performed, the plate 6 may be replaced, with the valve 13 preferably closed, and the valve 9 reopened. The valve 13 may then be opened and the oil permitted to run out 01? the overflow tank 7 1nto the main tank to displace, through the pump, or a pet cock (not shown), the air or gas introduced therein until the level 17 has dropped to its original value. Obviously the completely filled condition of tank 2 may also be determined it desired by a gauge glass (not shown) It should be understood that it is not desired to limit the invention claimed to the exact details of construction herein shown and described, for obvious modifications will occur to a person skilled in the art.

It is claimed and desired to secure by Letters Patent:

1. In combination, a normally closed receptacle including an oil tight closure, said receptacle containing heat produc ng apparatus, a body of oil completely filling sa d receptacle under normal ope 'atmg cond tions, an overflow tank, an Oll filled conduit connecting said overflow tank with said body of oil, said conduit passing through said closure, a valve in said conduit, a removable cover forming part of said closure, said cover being removable independently of said conduit, said cover being provided with a normally closed valve for admit-ting gas under pressure to said receptacle for the purpose of depressing the oil level in said receptacle.

2. In combination, a normally closed receptacle including an oil tight closure, said receptacle containing heat producing electrical apparatus, a body of oil completely filling said receptacle under normal. operating conditions, an overflow tank, an oil filled conduit connectin said overflow tank with said body of Oll, said conduit passing through said closure at a predetermined level, a valve in said conduit, a removable cover forming part of said closure, said cover being removable independently of said conduit, said cover having an opening at a higher level than said before mentioned predetermined level, a normally closed valve connected to said opening in said cover whereby gas under pressure may be introduced into said tank through said last named valve.

3. In combination, a normally closed re ceptacle including an oil tight closure, said receptacle containing heat producing electrical apparatus, a body of oil completely filling said receptacle under normal operating conditions, an overflow tank, an oil filled conduit connecting said overflow tank with said body of oil, said conduit passing through said closure at a predetermined level, a valve in said conduit, a removable cover forming part of said closure, said cover being removable independently of said conduit and disposed at a level below said valve, said cover having an opening at a higher level than said before mentioned predetermined level, a normally closed valve connected to said opening in said cover whereby gas under pressure may be introduced into said tank through said last named valve.

In testimony whereof the signature of the inventor is afiixed hereto.

LOUIS C. NICHOLS. 

